Zeolites are crystalline aluminosilicate compositions which are microporous and which are formed from corner sharing AlO2− and SiO2 tetrahedra. Numerous zeolites, both naturally occurring and synthetically prepared are used in various industrial processes. Synthetic zeolites are prepared via hydrothermal synthesis employing suitable sources of Si, Al and structure directing agents such as alkali metals, alkaline earth metals, amines, or organoammonium cations. The structure directing agents reside in the pores of the zeolite and are largely responsible for the particular structure that is ultimately formed. These species balance the framework charge associated with aluminum and can also serve as space fillers. Zeolites are characterized by having pore openings of uniform dimensions, having a significant ion exchange capacity, and being capable of reversibly desorbing an adsorbed phase which is dispersed throughout the internal voids of the crystal without significantly displacing any atoms which make up the permanent zeolite crystal structure. Zeolites can be used as catalysts for hydrocarbon conversion reactions, which can take place on outside surfaces of the zeolite as well as on internal surfaces within the pores of the zeolite.
In 1982, Wilson et al. developed aluminophosphate molecular sieves, typically called AlPOs, which are microporous materials that have many of the same properties of zeolites, but are silica free, composed of AlO2− and PO2+ tetrahedra, see U.S. Pat. No. 4,310,440. Subsequently, charge was introduced to the neutral aluminophosphate frameworks via the substitution of SiO2 tetrahedra for PO2+ tetrahedra to produce the SAPO molecular sieves, see U.S. Pat. No. 4,440,871. Another way to introduce framework charge to neutral aluminophosphates is to substitute [M2+O2]2− tetrahedra for AlO2− tetrahedra, which yield the MeAPO molecular sieves, see U.S. Pat. No. 4,567,029. It is furthermore possible to introduce framework charge on AlPO-based molecular sieves via the introduction both of SiO2 and [M2+O2]2− tetrahedra to the framework, giving MeAPSO molecular sieves, as shown in U.S. Pat. No. 4,973,785.
In these ground-breaking patents, metallophosphate materials with the LEV topology are disclosed. MAPO-35, a magnesium aluminophosphate material with the LEV topology is disclosed in U.S. Pat. No. 4,567,029 in which quinuclidine is employed as a structure directing agent. Likewise, U.S. Pat. No. 4,440,871 discloses SAPO-35, a silicoaluminophosphate that is also synthesized using the quinuclidine structure directing agent. In U.S. Pat. No. 4,973,785, the MeAPSO composition CoAPSO-35 is disclosed, which contains both cobalt and silicon in the framework in addition to Al and P and uses methylquinuclidine as the structure directing agent. After this early work, SAPO-35 was prepared using cyclohexylamine as a structure directing agent, see Lohse et. al, Crystal Research and Technology (1993), 28(8), 1101-1107. Subsequently, SAPO-35 has been prepared using hexamethyleneimine as a structure directing agent under a variety of conditions, including in ethylene glycol, see Venkatathri et al., JCS Faraday Transactions (1997), 93(18), 3411-3415) and in aqueous and fluoride media, see Prakash et al, Chem. Mater. (1998), 10, 932-941. Wang et al. have recently disclosed MAPO-35 materials containing Mg and synthesized using the N-methylpiperidine and 1, 2-diaminocyclohexane as structure directing agents, see Dalton Transactions (2012), 41(22), 6855-6860). Most recently Cao et al. have disclosed the preparation of SAPO-35 with the triethylmethylammonium structure directing agent, see US Pat. Appl. Publ. (2012), US 20120157741 A1.
In contrast to the above prior art, applicants have synthesized a variety of new materials and new structures using the very simple and commercially available ethyltrimethylammonium (ETMA+) and diethyldimethylammonium (DEDMA+) structure directing agents. One outcome of this investigation presented here is a new family of charged metallophosphate framework materials that contain a +3 valence metal, such as aluminum or gallium, and additionally at least one of a +2 valence metal, such as, for example, magnesium or zinc, and silicon, designated AlPO-67. When the +3 valence metal is Al, this corresponds to SAPO, MeAPO, and MeAPSO compositions. The AlPO-67 materials have the LEV topology that falls in the class of structures known as ABC-6 nets, see American Minerologist, 66, 777-788 (1981). The microporous AlPO-67 materials can be prepared with the simple ethyltrimethylammonium (ETMA+) and diethyldimethylammonium (DEDMA+) structure directing agents.